$28 would put it 12% above the call sell point of $25. To get a sell at $25 I had to start at a purchase price of $21.60, The $25 sale price is 15.74% above the buy price using 0% sell advice per Tom. The next sell is at $26.40 per the AIM spreadsheet, or 5.6% higher, and the next is at $28.70, 8.7% higher.
The setup in the spreadsheet is 100 shares, $1000 minimum trade size, 20% Cash and 0% sell safe.
If I understand you correctly you are saying that the minimum premium would be $300 for the call, right?